1. Field of the Invention
This invention relates to a current-limiting value setting method for an electric-vehicle traveling motor, and a device for practicing the method.
2. Description of the Related Art
Heretofore, in an industrial or electric-vehicle motor, a current-limiting value setting operation is carried out; more specifically, an adjusting operation comprised of setting a predetermined upper-limit current with respect to a rated current, which flows at the time of motor lock, is carried out. The current-limiting value is a value which is suitable for the actual application of the user or the design of the motor, and therefore it is determined for every user.
An arrangement and method for setting the current limit value will be described with reference to FIG. 3. The current flowing in the motor is chopper-controlled by a control element 1 which is connected in series to the armature A of the motor. The control element 1 is controlled by a control board (substrate) 2 including, among other things a micro-computer. The control board 2 is to chopper-control the motor current with a predetermined duty-cycle according to a motor current value detected by a current sensor CT and an instruction value provided by the accelerator (not shown). This current-value setting operation of the motor current is carried out as follows: With the motor locked and with the accelerator operated fully, the effective current of the motor is measured with a current meter 3 (provided separately). And a current-limiting value adjusting resistor (a variable resistor) VR in the control board 2 is adjusted such that the motor current value is equal to a predetermined current-limiting value.
However, the above-described conventional current-limiting value adjusting method and corresponding device suffer from the following problems: It is necessary to separately provide the current meter 3, and the accelerator operation section and the control board 2 are spaced apart from each other. Hence, it is necessary to provide two operators, a person for performing the accelerator operation for the motor current, and a person for adjusting the variable resistor VR in the control board 2. That is, the method and device are low in work efficiency.